.button_return {
    border-radius: 20px;
    background-color: dodgerblue;
    border: none;
    color: #FFFFFF;
    text-align: center;
    font-size: 14px;
    padding: 10px;
    width: 60px;
    cursor: pointer;
    position:fixed;
    top:25px;
    right:20px;
}

.button_return span {
    cursor: pointer;
    display: inline-block;
    position: relative;
    transition: 0.5s;
}

.button_return span:after {
    content: '«';
    position: absolute;
    color: rgba(255, 255, 255, 0);
    left: -3px;
    top: 10%;
}

.button_return:hover span {
    padding-left: 30%;
}

.button_return:hover span:after {
    color: white;
}

.button_top{
    border-radius: 20px;
    width: 40px;
    height: 40px;
    border: none;
    position:fixed;
    cursor: pointer;
    bottom:100px;
    right:15px;
    background-color: #eee;
    font-size: 20px;
    color: dodgerblue;
}

.button_top:hover{
    background-color: #ddd;
}

.button_down{
    border-radius: 30px;
    padding: 10px;
    width: 60px;
    height: 60px;
    border: none;
    position:fixed;
    cursor: pointer;
    top:20px;
    right:10px;
    background-color: dodgerblue;
    font-size: 15px;
    color: white;
    font-family: 幼圆;
    letter-spacing: 1px;
}

.button_down:hover{
    color: aliceblue;
}

.button1 {
    padding: 0;
    width: 45px;
    height: 22px;
    background-image: linear-gradient(to right,dodgerblue,steelblue);
    color: white;
    border: none;
    border-radius: 3px;
    cursor: pointer;
}

.button1:hover {
    background-image: linear-gradient(to right,steelblue,dodgerblue);
    color: midnightblue;
}